Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque
H,W=map(int,input().split(' '))
S=[list(input()) for i in range(H)]
S[0][0]=1
next  = deque([[0,0]])
ans = H*W
while next:
    x,y =next.popleft()
    s = S[x][y]
    for i,j in [[1,0],[0,1],[-1,0],[0,-1]]:
        if 0<=x+i<H and 0<=y+j<W and S[x+i][y+j]=='.':
            S[x+i][y+j]=s+1
            next.append([x+i,y+j])
for i in S:
    ans -=i.count('#')
if type(S[H-1][W-1])==str:
    print(-1)
else:
    print(ans-S[H-1][W-1])